The present invention relates to a plug valve and more particularly to a rotary plug valve which has a sealing ring on the surface of the plug to form a secure leakproof seal.
Plug valves are comprised of a valve body having an inlet and an outlet in axial alignment with each other and a plug opening intersecting the inlet and outlet. The plug opening is adapted to receive a plug which has an orifice therein adapted to be placed into axial alignment with the inlet and outlet to connect the two and thereby form a passageway for fluid to pass from the inlet through the orifice and to the outlet. The plug is adapted to be rotated to an inoperative position wherein the orifice is out of axial alignment with the inlet and outlet to disconnect the two and thereby stop the flow of fluid from the inlet to the outlet. In such plug valves a sealing ring (preferably an O-ring) is removably mounted in a sealing ring-receiving cavity on the plug wall to form a seal when the plug is rotated to its inoperative position. To replace the sealing ring the plug is removed from the housing and a new sealing ring is placed in the ring-receiving groove in the plug wall.
It has been found that in some existing plug valves, the sealing ring may not be easily replaced. In other valves, it is not possible to determine the direction of the flow from the position of the handle. Moreover, some existing plug valves do not have instant control of the flow while others are not multifunctional and do not have throttling capabilities. Furthermore, such existing plug valves may be inadvertently actuated which may be a safety hazard and others do not provide backup sealing rings. Moreover, it is difficult (if not impossible) for existing plug valves to be capable of being both panel and base mounted. In still others, the plug may be removed if the handle is missing. Some plug valves do not have straight through orifices so that maintenance, and especially roddability, is difficult. In other plug valves, it may be difficult to use standard O-rings.